Nowadays, projectors are widely used in many circumstances. For example, projectors can be used for presentations or video playback. For enhancing the visual effect, most projectors are employed to project images on large-sized screens. Recently, with increasing development of science and technology, a pico projector (also referred as a microdisplay) has been introduced into the market. The pico projector is designed to have small size and light weightiness. Generally, the pico projector is embedded into a portable electronic device (e.g. a mobile phone or a personal digital assistant), so that the pico projector may be directly utilized by the user. Alternatively, in some other situations, the pico projector is separated from the portable electronic device. Consequently, the pico projector may be operated after the pico projector is in communication with the portable electronic device. By mean of the pico projector, a corresponding image or data may be projected on a flat surface in order to be viewed by the user. In such way, the image may be displayed in a maneuverable and real-time manner.
Conventionally, the pico projector utilizes a reflective LCD panel produced according to an LCoS (liquid crystal on silicon) technology, which is also referred as an LCoS panel. The reflective LCD panel comprises an array of liquid crystal display units. The images shown on all liquid crystal display units are combined together to produce a resultant image. That is, after a light beam from a light source is irradiated on the LCoS panel, the light beam is reflected and modulated to produce the resultant image. Moreover, the light source used in the pico projector is for example a light emitting diode (LED).
Recently, the trend of designing the operating interface of the portable electronic device is toward succinctness. Consequently, a virtual keyboard utilizing an infrared sensing technology is developed. The portable electronic device with the virtual keyboard function may project a laser beam to create a virtual keyboard on a flat surface in front of the portable electronic device. For example, the virtual keyboard is a standard QWERTY keyboard. In other words, the contents of the virtual keyboard comprise the images of the keys of a physical keyboard. Moreover, the portable electronic device with the virtual keyboard function has an optical sensor for detecting the motion of the user's finger according to an infrared sensing technology. When a corresponding key image of the virtual keyboard is pressed or touched virtually by the user's finger, the portion of the laser beam corresponding to the position of the key image is blocked or sheltered by the user's finger. According to the blocked or sheltered portion of the light beam, the optical sensor can realize the operating status or the inputted content of using the virtual keyboard. Some conventional virtual keyboards are disclosed in for example US Patent Publication Nos. 20030174125 and 20100245235.
Similarly, the device for creating the virtual keyboard may be embedded into a portable electronic device or separated from the portable electronic device. In a case that the device for creating the virtual keyboard is embedded into the portable electronic device, the virtual keyboard may be directly projected on the flat surface to be operated. Whereas, in a case that the device for creating the virtual keyboard is separated from the portable electronic device, the operating status of the virtual keyboard may be transmitted from the virtual keyboard creating device to the portable electronic device (e.g. a personal computer, a notebook computer, a mobile phone or a tablet personal computer) in a wired transmission manner or a wireless transmission manner. By using the virtual keyboard, the portable electronic device may be operated more intuitively and conveniently. Under this circumstance, the applications of the portable electronic device are not restricted to the less number of physical keys or the hard-to-use graphics-based icons. Moreover, the use of the virtual keyboard can reduce the fabricating cost because the physical keyboard is exempted. Moreover, the use of the virtual keyboard can expand the range of the displaying zone and facilitate inputting commands.
From the above discussions, the function of the pico projector and the function of the virtual keyboard creating device are somewhat distinguished by the projecting approaches and the projecting positions. For integrating these two functions into the same portable electronic device, the projecting units for the pico projector and the virtual keyboard creating device should be disposed on different positions. Alternatively, the projecting directions of one projecting unit for the pico projector and the virtual keyboard creating device may be switched by a rotating mechanism. In such way, the fabricating cost or the overall volume is increased. Therefore, there is a need of providing a portable electronic device with the projecting function of a pico projector and the projecting function of creating a virtual keyboard by properly designing the hardware components, so that the fabricating cost and the overall volume are reduced.